This announcement was just the latest in a series of major
discoveries about the Red Planet, including the strongest
evidence yet of flowing, liquid water on the surface,
reported last September.

As of right now, NASA isn't providing many details about the
announcement, except for saying that they'll present "key
science findings" about Mars' atmosphere, which is still a
major mystery.

Scientists think that the Martian atmosphere was much thicker in
the past than it is today and has slowly been thinning out over
millions of years. Right now, Mars' atmosphere is less
than 1% the thickness of Earth's.

How thick the atmosphere used to be and how Mars lost most of it
is still an ongoing subject of research. An answer to these
questions could help scientists determine how habitable Mars was
in the distant past and what our chances are of finding evidence
of ancient life today.

Last year, NASA's Mars Atmosphere and Volatile Evolution
(MAVEN) spacecraft
began orbiting Mars for the sole purpose of examining its
atmosphere in unprecedented detail.

In particular, MAVEN is investigating how water and carbon
dioxide molecules disassociate into their individual, atomic
hydrogen, oxygen, and carbon components.

Some of these atoms escape the Martian atmosphere, so by looking
at their abundance changes over time, scientists can get a better
idea of what's causing these elements to separate from their
parent molecules and escape into space.

Here's who presented:

Michael Meyer, lead scientist for the Mars
Exploration Program at NASA Headquarters

Bruce Jakosky, Mars Atmosphere and Volatile
Evolution (MAVEN)
principal investigator at the Laboratory for Atmospheric and
Space Physics (LASP) at the University of Colorado, Boulder

Jasper Halekas, MAVEN Solar Wind Ion Analyzer
instrument lead at the University of Iowa, Iowa City